The Italian Maritime Rescue Coordination Center was using an airplane, a helicopter and four boats to search sea and coastal areas, the statement said.

Louis Abruzzo, the brother of one of the missing balloonists, said in a telephone interview from Albuquerque that both balloonists had "an awful lot of experience" and ballooning was his brother Richard's passion.

"He is an adventurer," Louis Abruzzo said.

Richard Abruzzo's wife, Nancy, issued a statement later in the day saying she was en route to Italy to "be involved as much as I can be with the search and rescue."

The event, billed as the world's oldest and most prestigious aeronautical race, this year features 20 teams from several countries and began September 25 in Bristol, England. The team that flies the farthest distance from the launch site wins.

Abruzzo said his brother and former New Mexico governor and longtime family friend Gary Johnson were scheduled to fly together in the America's Challenge during the Albuquerque Balloon Fiesta next week.

In an interview with Reuters on Thursday, Johnson said: "If there are any two people capable of coming out of this, it's Richard and Carol."

Additional reporting and writing by Ed Stoddard in Dallas; editing by Jonathan Oatis and Jerry Norton